Abstract
Meibomian gland lipid secretion is important to the stability of the tear film and ocular surface comfort. Changes in the tear film’s lipid layer thickness (LLT) after orthokeratology treatment may reflect underlying changes to the meibomian gland function. The purpose of this study was to investigate the features of the tear lipid layer in normal children and the effects of short-term orthokeratology treatment. Altogether, 163 myopic children (age: 10.7 ± 1.9 years, 8–15 years; 71 males) with no contact lens use history were enrolled in this study, of whom 56 were successfully fitted with orthokeratology lenses and completed the 1-month study. The tear film’s LLT (average, maximum, and minimum) and blinking pattern were measured by a LipiView® interferometer in 163 participants at baseline and in 56 orthokeratology participants at 1 week and 1 month after overnight lens wear. Results show that LLT (average) was 58.09 ± 21.66 nm in Chinese normal children. LLT was significantly correlated with rate of partial blinks at every follow-up (all p < 0.05 ). Compared to baseline, the LLT (average and minimum) and partial blinks (number and rate) at 1 week and 1 month after orthokeratology treatment both significantly increased, and the increase of LLT was correlated with elevation of rate of partial blinks. In conclusion, LLT was shown to be elevated after short-term overnight orthokeratology treatment and was related to change in rate of partial blinks. Further studies are needed to clarify the long-term effect and the underlying mechanism.
Highlights
Orthokeratology has been used worldwide since the advent of rigid, gas permeable lens material in the 1990s [1]. e high-Dk lens material combined with a paracentral reverse geometry design has made overnight wear possible and provides wearers with good visual acuity in the daytime [2, 3]
A previous study of over 29,500 contact lens fittings revealed that orthokeratology was gaining popularity over the past decade [4], and another study showed that over 25% of prescribed rigid contact lenses were orthokeratology lenses for children and adolescents, and 47% were for younger children (6–12 years old) [5]
As the first and foremost protection measure for the cornea, the tear film plays an important role in maintaining safety in contact lens wear by nourishing the cornea with oxygen, clearing the debris accumulated behind the lens, rewetting the ocular surface, and decreasing friction during blinking, etc
Summary
Orthokeratology has been used worldwide since the advent of rigid, gas permeable lens material in the 1990s [1]. e high-Dk lens material combined with a paracentral reverse geometry design has made overnight wear possible and provides wearers with good visual acuity in the daytime [2, 3]. ® LipiView interferometer (Johnson & Johnson, USA), which measures the LLT (average, minimum, and max) during natural blinking in a noninvasive manner with satisfactory repeatability, was used to evaluate the LLT and blinking pattern (number of blinks, number of partial blinks, and rate of partial blinks). For data of 163 normal participants at baseline, Pearson and Spearman correlation analyses were conducted to investigate the correlation between LLT (average, min, and max) and blink pattern (number of complete blinks, number of partial blinks, and rate of partial blinks). Correlation analysis of lipid layer thickness and blinking pattern was conducted for data of 56 participants undergoing orthokeratology treatment at every follow-up. Single-factor repeated measure ANOVA was used to analyze the change in lipid layer thickness (average, minimum, and max) and blinking pattern (number of blinks, number of partial blinks, and rate of partial blinks) 1 week and 1 month after orthokeratology treatment. SPSS software 22.0 (IBM Corp., Armonk, NY, USA) and R (4.0.2) were used
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